The present invention relates generally to a self-lubricating polymer composition that may be useful as a coating for an article, related methods of lubricating an article and using the lubricated article.
Examples of coated articles include electrical cable and fiber optic cable. Generally, known electrical cables include a conductor core wire and an insulative jacket disposed peripherally about the conductor core. At least some known conductor cores are constructed from copper, silver, gold, and aluminum, and at least some known insulative jackets are constructed from a polymeric material such as polyethylene, polypropylene, polyamide, or polyesters. While these known polymeric materials have desirable electrical resistivity, they may also have a high coefficient of friction making installation of the electrical cable through tight spaces and/or small openings, such as conduits, ducts, and building framing a challenge. For instance, the wires may become impinged and difficult to pull without excessive force.
One known method of reducing the coefficient of friction of electrical cable includes applying a pulling lubricant to the exterior surface of the electrical cable. Known pulling lubricants include gels, wax-based compositions, and polytetrafluoroethylene (PTFE)-based compositions. However, these known pulling lubricants must generally be applied to the exterior surface of the entire length of each electrical cable, which may be a time-consuming and tedious process.
Another known method of reducing the coefficient of friction includes forming a polymer composition comprising a lubricating material capable of migration or permeation within a formed polymer matrix and disposing it about the conductor core thereby forming an insulative jacket thereon. At least one known lubricating polymer composition is composed primarily of a nylon material and either an erucamide, a flowable silicone-based slip agent, or a PTFE-based slip agent. In this known configuration, the slip agent migrates or permeates to the outer surface of the insulative jacket as the wire is pulled during installation. Generally, the slip agents are included in the lubricating polymer composition at greater than about 1% by weight, and more typically from about 3-7% by weight. However, including slip agents at such high loads may result in reduced durability of the electrical wiring, increased costs, and susceptibility to failure at extreme temperatures.
Therefore a need exists for improvements for reducing the coefficient of friction between cables and contact surfaces of conduits, ducts, and building framing in order to avoid the problems associated with prior art cables including protracted installation time, cost associated with external lubricants, damage to cable attributed to impingement and/or excessive pulling force, and burn-through damage to cable jackets caused by frictional heating generated by contact between the cable exterior surface and a second surface (e.g., conduit or duct).